When Sphinx of Uthuun enters the battlefield, reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

You (not your opponent) choose which pile to put into your hand and which to put into your graveyard.

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A pile can have no cards in it. In this case, you’ll choose whether to put all the revealed cards into your hand or into your graveyard.

9/22/2011

If your library has fewer than five cards, you reveal all the cards in it, then your opponent separates them into two piles.

9/22/2011

In multiplayer games, you choose an opponent to separate the cards when the ability resolves. This doesn’t target that opponent. Because the cards are revealed, all players may see the cards and offer opinions.